1. Field of the Invention
The present invention relates to new compositions based on polyamide, flameproofed with red phosphorus, which are intended in particular for the manufacture of articles for the electrical or electronics industry.
2. Description of the Prior Art
It is known that the addition of red phosphorus to polyamide-based compositions makes it possible to achieve a high degree of flameproofing. (French Patent Application published under No. 2,218,364). However, the use of red phosphorus presents a serious disadvantage, namely the liberation of phosphine during the heating which accompanies the moulding of the polymer. It is also known that it is possible to restrict this disadvantage by incorporating into the compositions certain substances which fix the phosphine, such as the compounds of the group MoS.sub.2, PbO.sub.2, AgNO.sub.3, HgCl.sub.2, FeCl.sub.3.6H.sub.2 O, CuO or active charcoal, (the abovementioned French patent application, which particularly recommends the use of copper oxide and active charcoal).
It has also been proposed to further improve the result obtained with these oxides by coating the red phosphorus with various polymers.
In fact, the use of the abovementioned products, and in particular of copper oxide, makes it possible considerably to reduce the liberation of phosphine. On the other hand, the polyamides which are flameproofed with red phosphorus and contain copper oxide exhibit a rather low arcing resistance (in terms of Standard Specification NF/C 26,220) and their use in the manufacture of components which are intended for the electrical or electronics industries is therefore not recommended.